I've been teaching physics for 20 years. I'm good at it. The quality of instruction in this video is stunningly good. There is no point in me even developing a lesson or lecture on this topic, as it simply could not be done better or more clearly than this.
Mr. P, you never cease to amaze me. I started watching your videos as a sophomore when I took Honors Physics 1. Your videos helped me score a 5 on the AP Physics 1 exam. You made me love and enjoy physics so much that I decided to take the AP exam without taking the class. Next year, I will be taking AP Physics C as a senior. I cannot wait to continue my physics journey with you. ❤️
This is an awesome comment. Thank you!!!! Any chance you could please do what I have asked people to do in the following video? bit.ly/2y4tOCA It would be a great way to show your appreciation! Also, I love AP Physics C.
The ball gets its angular momentum from the diagonal between the lazy Suzan and the very point where ball hits. I don't know how to explain mathematically like you but you got the point which should be correct from my point of view. I've got this question and explanation from the other video of yours with the same ball and the same board. When you drew that line from the pivotal point to the point where ball hits I understood immediately why the ball turned back on a slightly circular path instead of a straight one. That was the reason but I just cannot explain it mathematically.
If we took another reference pivot point the radius will change and so the angular momentum of the particle. so considering this fact will I be wrong if I conclude the angular momentum of the particle is not instinct to the particle rather found relative to the pivot point that we can arbitrarily choose. In other words "will the point particle still have angular momentum if there was no reference point? or is it the linear momentum converted to angular momentum during the collision?". In short "Is the angular momentum of the particle ideal assumption (to ease our calculation) or actual in the physical world?"
Did any brilliant catch it? That L = p × R, where L and p is angular and liner momentum and R is the distance from the AOR to the CM. Also × is cross product!! I know it's derivation! Mr. Jonathan, please allow me! I derived this on my own before this video and now it's confirmed I was correct! L = I w For a point mass like an electron, I = MR^2 L = w M R^2 But theta is nothing but 2 pi / T (I'm driving this for an electron in Newtonisn Mechanics) Then L = 2 pi R/ T times M R But 2 pi R/ T is just tangential velocity so: L = v M R L = Mv R Where Mv = p L = pR which is L= p × R Voila!
My school does not provide AP physics C Mechanics, but I have found a teacher that is willing to help me take it an independent study, with one stipulation. I need to find resources online that we can construct a curriculum around. I was wondering if you knew of any resources that can track homework, assessments and such
At 7:50, you show an angle theta in the diagram. Having the ball strike the board the same way it does on the left would cause the largest angular momentum being that sin(90) = 1, but the angle shown in the diagram doesn't look like 90 degrees. Is this just to show how to measure the angle used, or do I just have a walnut-sized brain?
I am confused about the theta angle. I mean the theta angle is the measure of angle between the 'r' vector and the velocity 'v' vector but this angle changes when the ball keeps moving. So when is the right time to take the angle. For example: When the ball roll down perpendicular relative to the board the angle theta gradually increases as the ball approaches the board. In fact I think it will reach ~90 degrees just before the collision. So "When is the right time to take/measure theta"?
@@FlippingPhysics thanks. but I have another question: Will the point particle(the ball in this case) still have angular momentum if the wooden board was not there. I mean what would the axis of rotation be?
@@debotrialaccount469 You select any point of your choice, in an inertial reference frame, as the origin of angular momentum. It is an arbitrary choice, and the value of angular momentum is only meaningful in the context of knowing what the reference point is. Conservation of angular momentum, the most common application of why we want to know it, is still valid no matter what point is selected, as long as the reference point is not accelerating.
w.r.t. the angular momentum which the board has after the collision, why can't the cause be the force of the ball hitting the board? I don't disagree that the ball has angular momentum, but I'm not sure how this example 'proves' it - since a force (with no angular momentum) applied to that spot of the board will cause the board to rotate as well. Maybe I'm missing something.?.
The cause certainly is the force of the ball hitting the board. Angular momentum and its conservation, is a shortcut for keeping track of the effects of this force. If we wanted to stick to first principles and not use conservation of angular momentum to solve this problem, we would need to know the details of force vs time during the impact, and correspondingly calculate the torque on the board at every point in time, and integrate the corresponding angular acceleration.
You know what sir? I appreciate your efforts very much..that's a lot of effort to create this video..I could simply understand your explanation...thank you very much.... *From deepest of my heart..
I've been teaching physics for 20 years. I'm good at it. The quality of instruction in this video is stunningly good. There is no point in me even developing a lesson or lecture on this topic, as it simply could not be done better or more clearly than this.
Wow. Curt, thank you for this comment. Absolutely made my day!
I wonder what textbook you have chosen.
@@curtbixel7806 For my AP Physics C class I use Physics for Scientists and Engineers by Serway and Jewett 6th Edition Copyright 2004 ISBN 0534408427
Mr. P, you never cease to amaze me. I started watching your videos as a sophomore when I took Honors Physics 1. Your videos helped me score a 5 on the AP Physics 1 exam. You made me love and enjoy physics so much that I decided to take the AP exam without taking the class. Next year, I will be taking AP Physics C as a senior. I cannot wait to continue my physics journey with you. ❤️
This is an awesome comment. Thank you!!!! Any chance you could please do what I have asked people to do in the following video? bit.ly/2y4tOCA It would be a great way to show your appreciation!
Also, I love AP Physics C.
these are just getting better and better!! thank you!
It is nice to know other people think the videos are getting better (I think it's true, however, I've got a mild bias going.)
Amazing video! So beautifully explained. Hats off to you, Mr P!
Thanks for the love!
The ball gets its angular momentum from the diagonal between the lazy Suzan and the very point where ball hits. I don't know how to explain mathematically like you but you got the point which should be correct from my point of view.
I've got this question and explanation from the other video of yours with the same ball and the same board. When you drew that line from the pivotal point to the point where ball hits I understood immediately why the ball turned back on a slightly circular path instead of a straight one. That was the reason but I just cannot explain it mathematically.
Amazing way of teaching! Even though I haven't studied this topic so far, I kind of understood it.
These videos deserve millions of views
someday?
Great, amusing and well demonstrated.
Brilliant demonstration!
This is high praise coming from you, my friend. Thanks!
this video would have helped me with the frqs from this years exam
the one about the ball sliding with friction :(
Really nice explanation!
If we took another reference pivot point the radius will change and so the angular momentum of the particle. so considering this fact will I be wrong if I conclude the angular momentum of the particle is not instinct to the particle rather found relative to the pivot point that we can arbitrarily choose. In other words "will the point particle still have angular momentum if there was no reference point? or is it the linear momentum converted to angular momentum during the collision?". In short "Is the angular momentum of the particle ideal assumption (to ease our calculation) or actual in the physical world?"
Did any brilliant catch it? That L = p × R, where L and p is angular and liner momentum and R is the distance from the AOR to the CM. Also × is cross product!!
I know it's derivation! Mr. Jonathan, please allow me! I derived this on my own before this video and now it's confirmed I was correct!
L = I w
For a point mass like an electron, I = MR^2
L = w M R^2
But theta is nothing but 2 pi / T (I'm driving this for an electron in Newtonisn Mechanics)
Then
L = 2 pi R/ T times M R
But 2 pi R/ T is just tangential velocity so:
L = v M R
L = Mv R
Where Mv = p
L = pR which is L= p × R
Voila!
SIR
PLS MAKE A VIDEO OF WHERE THE TORQUE IS 0 IN CASE OF CONSERVING ANGULAR MOMENTUM IN ROLLING ON ROUGH AND SMOOTH SURFACE
PLSS🙏
excellent
Please review more full AP Physics C tests
My school does not provide AP physics C Mechanics, but I have found a teacher that is willing to help me take it an independent study, with one stipulation. I need to find resources online that we can construct a curriculum around. I was wondering if you knew of any resources that can track homework, assessments and such
I love this
At 7:50, you show an angle theta in the diagram. Having the ball strike the board the same way it does on the left would cause the largest angular momentum being that sin(90) = 1, but the angle shown in the diagram doesn't look like 90 degrees. Is this just to show how to measure the angle used, or do I just have a walnut-sized brain?
Please watch this: www.flippingphysics.com/angular-momentum-triangle.html
I think it will help clear up your confusion.
I am confused about the theta angle. I mean the theta angle is the measure of angle between the 'r' vector and the velocity 'v' vector but this angle changes when the ball keeps moving. So when is the right time to take the angle.
For example: When the ball roll down perpendicular relative to the board the angle theta gradually increases as the ball approaches the board. In fact I think it will reach ~90 degrees just before the collision. So "When is the right time to take/measure theta"?
I have an entire video about the angle: www.flippingphysics.com/angular-momentum-triangle.html
@@FlippingPhysics thanks.
but I have another question:
Will the point particle(the ball in this case) still have angular momentum if the wooden board was not there. I mean what would the axis of rotation be?
@@debotrialaccount469 You select any point of your choice, in an inertial reference frame, as the origin of angular momentum. It is an arbitrary choice, and the value of angular momentum is only meaningful in the context of knowing what the reference point is. Conservation of angular momentum, the most common application of why we want to know it, is still valid no matter what point is selected, as long as the reference point is not accelerating.
This is...good.
thank ... s
w.r.t. the angular momentum which the board has after the collision, why can't the cause be the force of the ball hitting the board? I don't disagree that the ball has angular momentum, but I'm not sure how this example 'proves' it - since a force (with no angular momentum) applied to that spot of the board will cause the board to rotate as well. Maybe I'm missing something.?.
The cause certainly is the force of the ball hitting the board. Angular momentum and its conservation, is a shortcut for keeping track of the effects of this force. If we wanted to stick to first principles and not use conservation of angular momentum to solve this problem, we would need to know the details of force vs time during the impact, and correspondingly calculate the torque on the board at every point in time, and integrate the corresponding angular acceleration.
thanks im looking forward to invent time machine......
My guess is you should look backward instead.
You know what sir? I appreciate your efforts very much..that's a lot of effort to create this video..I could simply understand your explanation...thank you very much.... *From deepest of my heart..
THAAAAAAAAAANKS